In many audio-video systems today, a “settop box” is used to receive communicated services and to interface with the user. Originally, the primary role for settop boxes' was to allow conditional access to the communicated services. Conditional access (CA) refers generally to a technology used to control access to communicated services such as television programming. Several different CA schemes currently exist. The transmissions conveying such communicated services are typically scrambled or encrypted, and only authorized users are provided with means to descramble or decrypt the transmissions. Scrambling typically involves modifying a transmission signal by, for example, removing synchronization pulses. Encryption typically involves modifying digital data conveyed by the transmission signal according to a particular cryptographic algorithm. Conditional access has been used for many years to provide exclusive access to premium television channels and special broadcasts (e.g., sporting events and pay-per-view movies). Conditional access can also be used to provide exclusive access to digital radio broadcasts, digital data broadcasts, and interactive services. Known CA technologies for scrambling or encrypting television transmissions include VideoCrypt™ (Thomson Consumer Electronics, S A FR), VideoCipher™ and DigiCipher™ (NextLevel Systems, Inc., Chicago, Ill.).
A typical CA system used to scramble or encrypt television programming generally includes CA encoding equipment integrated into broadcast equipment (e.g., cable, satellite, or terrestrial broadcast equipment) at a service provider's location. In general, the CA encoding equipment modifies (i.e., scrambles or encrypts) information conveyed by a transmission signal produced by the broadcast equipment. Where the CA encoding equipment employs encryption, the CA encoding equipment encrypts digital data (e.g., digitized video and audio information), and the broadcast equipment transmits a signal conveying the encrypted digital data to the subscribers. The CA encoding equipment may also insert messages into the transmission signal that provide information necessary for decryption of the encrypted digital data.
The typical CA system also includes CA decoding equipment at each subscriber's location. The CA decoding equipment typically includes a box receiving the transmission signal capable of being coupled to a television set or other display means. Such boxes are commonly referred to as “settop boxes” or integrated receiver decoders (IRDs). A typical settop box decrypts the encrypted digital data in the transmission signal, converts the digital data to analog signals (e.g., analog video and audio signals), and provides the analog signals for display on a television set or other display means.
Whether or not a settop box includes this capability, current settop boxes are continually advancing to provide further relatively sophisticated functionality to the audio-video systems in which they are coupled. For example, the settop box may provide menus via the display or television to allow the user to control and interact with the system via a user-friendly, graphical user interface (GUI). Additionally, the settop box may provide personal video recording (PVR) capabilities in which communicated services may be recorded and played back at a later, more convenient, time.
To provide these enhanced control and interfacing services via a settop box, the settop box must generally incorporate increasingly sophisticated hardware and software. Accordingly, existing hardware and software capabilities of settop boxes can be further enhanced to provide even more advanced functionality, and to increase the users' control and enjoyment of the system to which the settop box is coupled.